This invention relates to the problem of monitoring water leakages occurring in commercial and household water systems. In a more specific aspect the invention pertains to apparatus for automatically cutting off the water supply upon the detection of a leak.
A problem of great concern is that of water damage to carpeting, flooring, walls and furniture due to water leakage resulting from faulty water heaters, defective plumbing fixtures, appliances such as washing machines and dishwashers, as well as damage resulting from such unforeseen disasters as earthquakes and fires. The seriousness of this problem is evidenced by large a volume of patents.
By way of example U.S. Pat. No. 5,240,022 discloses an automatic shut-off. U.S. Pat. No. 4,845,472 provides an apparatus which responds to the sensing of water leakage from a water line of a hot water system. U.S. Pat. No. 5,190,069 utilizes wires embedded in insulation tape carrying leak detecting liquid sensing elements. U.S. Pat. No. 5,229,750 utilizes a float and solenoid valve combination to control a cut-off in the event of a water leak. U.S. Pat. No. 5,632,302 discloses an overflow protection shut-off device for use with a water heater.
An investigation of this prior art shows that most of the patents, such as U.S. Pat. No. 4,845,472, U.S. Pat. No. 5,428,347, and U.S. Pat. No. 5,655,561 generate audible alarms to signal a detected leak. Of these U.S. Pat. No. 4,845,472, U.S. Pat. No. 5,428,347, and U.S. Pat. No. 5,655,561 additionally disclose the use of solenoid-actuated valves in the water supply line. U.S. Pat. No. 5,229,750 and U.S. Pat. No. 5,632,302 also disclose the use of solenoid-actuated valves to cut off a water supply. U.S. Pat. No. 5,029,605 points out that deposits that accumulate in pipes and valves over a period of time may impede the actuation of solenoid-type valves. Also avoiding the use of solenoid actuated valves is U.S. Pat. No. 5,240,022, which incorporates a ball valve in the water supply line. To hold the ball valve in an open position it is coupled to a rotor and a spring is attached to the rotor exerting a counterclockwise torque on the rotor. The rotor is then locked in a valve-open position by a latching arm. The end of the latching arm contacts a trip arm that receives its retaining torque from a wire spring. A trip wire actuates the trip arm. This trip wire is a metallic memory alloy wire which contracts when heated. Heating is effected by a circuit actuated by the water detector. As a consequence the latch aim is released and the rotor rotates to a valve-closed position.
Also of interest for disclosing a ball valve is U.S. Pat. No. 5,334,973. This valve controls flow into a hot water tank by using a mechanical drive in conjunction with a multilayer moisture sensor which encases the water tank liner.
While U.S. Pat. No. 5,240,022 overcomes the problems of solenoids, it is subject to several disadvantages. In addition to requiring a rotor, a latching arm, a trip arm, a trip wire and various springs, allowances had to be made for the ball valve high rotational forces, primarily due to the friction between the valve ball and the O-ring seals. In addition the ball valve must be reset to its open position by turning a knob, which frequently is not always easy. The invention herein provides an improvement which permits the use of a ball valve without the problems encountered in U.S. Pat. No. 5,240,022. All of the above mentioned patents are incorporated herein by reference.
This leak detection and shut-off apparatus is an improvement over the known prior art apparatus.